LONDON, England -- A British man wanted in the United States for allegedly carrying out "the biggest military computer hack of all time" has been granted bail.

Gary McKinnon, 39, of north London faces extradition over claims he gained illegal access and made alterations to 53 U.S. military and NASA computers over a 12-month period from 2001 to 2002.

McKinnon, who is contesting the extradition request, appeared at Bow Street Magistrate's Court in London on Wednesday.

District Judge Christopher Pratt granted McKinnon bail to reappear for an extradition hearing on July 27.

As conditions of his bail, he was ordered to provide £5,000 security, report to his local police station, not apply for any international travel documents and not use any computer equipment allowing him to access the Internet, the UK's Press Association reported.

Janet Boston, representing the U.S. government, told the court: "On one instance, the U.S. Army's military district of Washington network became inoperable."

McKinnon was first arrested in 2002 but action against him was discontinued.

Outside court, his solicitor Karen Todner said McKinnon was disappointed it had taken the authorities this long to bring him to court.

"This decision for extradition is driven by the American government. Mr. McKinnon intends to contest this case most vigorously," Todner said.

"Of particular concern to him is the treatment of other British nationals under the American judicial system which inspires little confidence.

"We believe that as a British national, he should be tried here in our courts by a British jury and not in the U.S."

Using software available for download on the Internet, McKinnon -- an unemployed computer systems administrator -- allegedly hacked into almost 100 networks operated by the U.S. Army, Navy, Air Force and the Pentagon.

The U.S. government estimated the the cost of tracking and correcting the alleged problems to be about $1 million (£570,000).

McKinnon was indicted in 2002 by a U.S. grand jury on eight counts of computer-related crimes in 14 different states.

The indictment said he hacked into an Army computer at Fort Myer, Virginia, obtained administrator privileges and transmitted codes, information and commands before deleting about 1,300 user accounts.

It alleged he also "deleted critical system files" on the computer, copied a file containing usernames and encrypted passwords for the computer and installed tools to gain unauthorized access to other machines.

Further allegations include that he modified Navy and Air Force computers and copied other files.

He was accused of hacking into a network of 300 computers at the Earle Naval Weapons Station in Colts Neck, New Jersey, and stealing 950 passwords.

Because of the alleged break-in, which occurred immediately after the September 11, 2001 terrorist attacks, the whole system was effectively shut down for a week, officials said at the time.

Speaking at the time of the indictment in 2002, Paul McNulty, the U.S. attorney for the Eastern District of Virginia, said: "Mr. McKinnon is charged with the biggest military computer hack of all time."

Many of the computers he allegedly broke into were protected by easy-to-guess passwords, investigators said.

He downloaded sensitive, but not classified, information about subjects that included Navy shipbuilding and munitions, it was alleged.

But there was no evidence any information was offered to foreign governments or terrorist organizations, McNulty said in 2002.

If extradited and found guilty, McKinnon -- known on the Internet as "Solo" -- faces a maximum penalty of five years in prison and a $250,000 fine.

A spokeswoman for Scotland Yard said McKinnon was arrested at 6.30 p.m. Tuesday by officers from the Metropolitan Police Service Extradition Unit.